Comparison of techniques for detecting T-cell acute lymphocytic leukemia

Three versions of the E-rosette test, one using untreated sheep erythrocytes at 37 degrees C, another using such cells at 4 degrees C, and a third using sheep erythrocytes treated with S-(2-aminoethyl)isothiouronium bromide hydrobromide (AET), were applied to each of 72 bone marrow specimens from as many unselected patients with untreated acute lymphocytic leukemia (ALL). The same specimens were also examined for T-cell antigens, based on reactivity with an antithymocyte serum. Lymphoblasts in eight ALL specimens formed E rosettes at 37 degrees C; no other E-positive specimens were identified when the assay was done at 4 degrees C. With AET-treated erythrocytes, lymphoblasts from these eight specimens and six additional specimens readily formed rosettes. T-cell antigens were detectable in all specimens positive for rosette formation withe untreated erythrocytes, in four of the six specimens positive for rosette formation with AET-treated erythrocytes, and in four specimens that showed no rosette formation under any of the experimental conditions used. Altogether, 18 specimens contained lymphoblasts with one or more surface markers characteristic of T-cell leukemia. These findings indicate that more specimens are likely to be identified at T-cell luekemias when E-rosette tests of increasing sensitivity and assayss for T-cell antigens are used. Some leukemic blasts do not possess the full array of membrane receptors and antigens usually associated with T cells. A combination of E-rosette tests and serologic tests is necessary to determine reliably the relationship of the test specimen to either T-cell ALL or common ALL and to establish the clinical significance of blasts that express membrane properties intermediate between those of T-cell ALL and common ALL.